1. Field of the Invention
The present invention relates to antennas, and more particularly, to an integrally formed and symmetrical plated inverted-F antenna (PIFA) adapted for use in wireless network devices, and a wireless network device with the antenna.
2. Description of the Prior Art
Referring to FIG. 1, which is a perspective view of a typical wireless network device 10. The wireless network device 10 usually includes a main body 11, an internal circuit apparatus 12 located inside the main body 11, a connector portion 13 located at one end of the main body 11 for connecting an external main unit (not shown), and a radio signal receive/transmit portion 14 located at an end of the main body 11 opposing the connector portion 13. Generally, the radio signal receive/transmit portion 14 is provided with an outer casing that is made of a non-metal material. When the wireless network device 10 is connected to the external main unit, the radio signal receive/transmit portion 14 must be exposed outside of the external main unit so as to effectively receive and transmit radio signals.
Referring to FIG. 2, which is a schematic view of a conventional internal circuit apparatus 20 of wireless network device. The conventional internal circuit apparatus 20 of wireless network device includes a substrate 21, a control circuit 22 located on the substrate 21, a ground portion 23 covering a predetermined area of the substrate 21, and an antenna unit 24 electrically connected to the control circuit 22. The conventional antenna unit 24 illustrated in FIG. 2 includes a first antenna 241 and a second antenna 242 located at two lateral sides of the substrate 21, respectively. Since the antenna unit of this conventional internal circuit apparatus 20 is designed as printed antenna printed on the substrate 21, by making different shapes of the first antenna 241 and the second antenna 242, the antenna unit can achieve a better radiation field profile and higher gain on an X-Y plane (horizontal plane), but there is little room for further improvement of antenna gain along a vertical Z direction. However, the design of current wireless network device tends to be vertical stand type, so as to reduce the space occupied by the wireless network device, as well as to make the appearance of the wireless network device more modern and high-tech. It is obvious that the conventional printed antenna cannot meet the requirement for the vertical stand type wireless network device due to the poor gain along the vertical Z direction.
For example, referring to FIG. 3, which is a chart showing a radiation field profile measured on an X-Y plane of the first antenna of the conventional antenna unit 24 as shown in FIG. 2. From the radiation field profile of FIG. 3, it can be seen that the peak gain of the first antenna 241 along the vertical direction is only −15.89 dBi, which is apparently lower than the minimum standard accepted by consumers (a general requirement is that the gain should be at least greater than −10 dBi). Thus, there is still room for improvement regarding to the design of antenna, which is also critically important for meeting the need for high performance antenna from consumers.